1. Field of the Invention
The present invention relates to a ventilator apparatus for supplying air from a source of pressurized air between a dryer and a web supported by a felt extending around a roll.
More specifically, the present invention relates to a ventilator apparatus for supplying air from a source of pressurized air between the dryer and a web supported by a felt extending around a roll of a single tier drying section of a paper machine.
2. Information Disclosure Statement
In the operation of a Bel-Champ type single tier drying section, the web supported by a dryer felt extends around a heated drying cylinder. Subsequently, the dryer felt diverges relative to the surface of the drying cylinder and thereafter extends around a roll such as a vacuum roll. Bel-Champ is a common law trademark of Beloit Corporation.
The web follows the felt when the felt diverges relative to the drying cylinder. However, there is a tendency for a slight underpressure to be generated at the diverging nip defined between the surface of the dryer and the diverging dryer felt. Such slight underpressure tends to cause a flow of ambient air toward such diverging nip and such flow of ambient air is detrimental to the movement of the web contiguously with the felt.
Additionally, such flow of ambient air flows in from the edges of the felt and has a tendency to generate edge flutter of the web.
Also, there exists a tendency of the web to follow the heated surface of the dryer cylinder rather than the surface of the diverging felt.
The present invention overcomes the aforementioned problems associated with the prior art arrangements by the provision of a ventilator apparatus, disposed in the vicinity of the aforementioned diverging nip. The ventilator apparatus which is connected to a supply of pressurized air generates a current of air which is directed into the diverging nip. The current of air compensates for any underpressure generated by the felt when diverging away from the dryer so that fluttering of the web is inhibited.
Therefore, it is a primary objective of the present invention to provide a ventilator apparatus which overcome the problems associated with the prior art drying section arrangements and which makes a considerable contribution to the art of drying paper.
Other objects and advantages of the present invention will be readily apparent to those skilled in the art by a careful consideration of the detailed description contained hereinafter taken in conjunction with the annexed drawings.